Date Tree Waste-Based Binary Fibrous Mix for Moderate to Severe Loss Control

ABSTRACT

A date tree fiber mix lost circulation material (LCM) is provided. The date tree fiber mix LCM may include includes date tree trunk fibers produced from date tree trunks and date tree leaf and leaf stem fibers produced from date tree leaves and leaf stems. The LCM include a mix of 30% by weight date tree trunk fibers and 70% date tree leaf and leaf stem fibers, 40% by weight date tree trunk fibers and 60% date tree leaf and leaf stem fibers, 50% by weight date tree trunk fibers and 50% date tree leaf and leaf stem fibers. Methods of lost circulation control using and manufacture of a date tree fiber mix LCM are also provided

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.62/436,211 filed Dec. 19, 2016, and titled “DATE TREE WASTE-BASED BINARYFIBROUS MIX FOR MODERATE TO SEVERE LOSS CONTROL.” For purposes of UnitedStates patent practice, this application incorporates the contents ofthe Provisional Application by reference in its entirety.

BACKGROUND Field of the Disclosure

The present disclosure generally relates to controlling lost circulationin a wellbore during drilling with a drilling fluid. More specifically,embodiments of the disclosure relate to a lost circulation material(LCM).

Description of the Related Art

Lost circulation is one of the frequent challenges encountered duringdrilling operations. Lost circulation can be encountered during anystage of operations and occurs when drilling fluid (such as drillingmud) pumped into a well returns partially or does not return to thesurface. While some fluid loss is expected, excessive fluid loss is notdesirable from a safety, an economical, or an environmental point ofview. Lost circulation is associated with problems with well control,borehole instability, pipe sticking, unsuccessful production tests, poorhydrocarbon production after well completion, and formation damage dueto plugging of pores and pore throats by mud particles. In extremecases, lost circulation problems may force abandonment of a well.

Lost circulation can occur in various formations, such as naturallyfractured formations, cavernous formations, and high permeableformations. Lost circulation can be categorized by the amount of fluidor mud lost as seepage type, moderate type, severe type, and total loss.The extent of the fluid loss and the ability to control the lostcirculation with an LCM depends on the type of formation in which thelost circulation occurs. Formations with low permeability zones, thatis, those with microscopic cracks and fissures, usually have seepagetype lost circulation. Other formations may experience lost circulationif an improper mud weight is used while drilling.

SUMMARY

Lost circulation materials (LCMs) are used to mitigate the lostcirculation by blocking the path of the drilling fluid (such as drillingmud) into the formation. The type of LCM used in a lost circulationsituation depends on the extent of lost circulation and the type offormation. Different types of LCMs such as granular, fibrous and flakymaterials are frequently used either alone or in combination to controlloss of circulation. For example, fibrous LCMs may include cedar fibers,wood fibers, jute fibers, or synthetic fibers to control loss ofcirculation.

Costs incurred in loss circulation situations may be due to losses ofdrilling fluids, losses of production, and the costs of LCMs, includingimportation of LCMs to drilling locations. Additionally, lostcirculation can cause environmental problems if drilling fluids or LCMsinteract with the environment surrounding the reservoir. Themanufacture, use, and disposal of some conventional LCMs may pose a riskto sensitive environments, such as marine environments because they arenot biodegradable and can be toxic to marine life.

Embodiments of the disclosure include a date tree fiber mix LCMcomposition used to mitigate or prevent lost circulation in a well, aswell as provide seepage control and minimize or prevent fluid loss. Thefibers of the date tree fiber LCM may form a stack of interweaved fibersin the gap or mouth of fractures and other openings of a loss zone. Thenetworked and interweaved fibers create a mat-like porous structure overthe fractures or other openings that significantly reduces the size ofthe openings. The reduction in size of the fractures, pores, gaps,fissures, cracks, and other openings only allows the escape of the fluidphase of a drilling mud, not the whole mud in an active mud system or inan LCM pill. The infiltration and deposition of colloidal and other mudsolids into and at the mat-like structure creates an effective barrierto prevent the loss of whole mud in the loss zone.

In one embodiment, a method to control lost circulation in a lostcirculation zone in a wellbore is provided. The method includesintroducing an altered drilling fluid into the wellbore such that thealtered drilling fluid contacts the lost circulation zone and reduces arate of lost circulation into the lost circulation zone. The altereddrilling fluid includes a drilling fluid and a lost circulation material(LCM). The LCM includes a first plurality of fibers produced from datetree trunks and a second plurality of fibers produced from at least oneof date tree leaves and date tree leaf stems. In some embodiments, thealtered drilling fluid consists of the drilling fluid and the LCM. Insome embodiments, the LCM consists of the plurality of fibers producedfrom date tree trunks and the plurality of fibers produced from at leastone of date tree leaves and date tree leaf stems. In some embodiments,the first plurality of fibers are 30% by weight of the LCM and thesecond plurality of fibers are 70% by weight of the LCM. In someembodiments, the LCM has a concentration of at least 30pounds-per-barrel (ppb) in the altered drilling fluid. In someembodiments, each of the first plurality of fibers produced from datetree trunks has a diameter in the range of 0.4 millimeters (mm) to about0.8 mm. In some embodiments, each of the second plurality of fibersproduced from at least one of date tree leaves and date tree leaf stemshas a diameter in the range of 0.5 millimeters (mm) to about 1 mm. Insome embodiments, the first plurality of fibers include a firstplurality of untreated fibers and the second plurality of fibersproduced include a second plurality of untreated fibers.

In another embodiment, an altered drilling fluid includes a drillingfluid and a lost circulation material (LCM). The LCM includes a firstplurality of fibers produced from date tree trunks and a secondplurality of fibers produced from at least one of date tree leaves anddate tree leaf stems. In some embodiments, the LCM consists of the firstplurality of fibers produced from date tree trunks and the secondplurality of fibers produced from at least one of date tree leaves anddate tree leaf stems. In some embodiments, the first plurality of fibersinclude 30% by weight of the LCM and the second plurality of fibersinclude 70% by weight of the LCM. In some embodiments, the LCM has aconcentration of at least 30 pounds-per-barrel (ppb) in the altereddrilling fluid. In some embodiments, each of the first plurality offibers produced from date tree trunks has a diameter in the range of 0.4millimeters (mm) to about 0.8 mm. In some embodiments, each of thesecond plurality of fibers produced from at least one of date treeleaves and date tree leaf stems has a diameter in the range of 0.5millimeters (mm) to about 1 mm. In some embodiments, the first pluralityof fibers include a first plurality of untreated fibers and the secondplurality of fibers produced include a second plurality of untreatedfibers.

In another embodiment, a lost circulation material (LCM) compositionincludes a first plurality of fibers produced from date tree trunks anda second plurality of fibers produced from at least one of date treeleaves and date tree leaf stems. In some embodiments, the LCMcomposition consists of the first plurality of fibers produced from datetree trunks and the second plurality of fibers produced from at leastone of date tree leaves and date tree leaf stems. In some embodiments,the first plurality of fibers are 50% by weight of the LCM and thesecond plurality of fibers are 50% by weight of the LCM. In someembodiments, each of the first plurality of fibers produced from datetree trunks has a diameter in the range of 0.4 millimeters (mm) to about0.8 mm. In some embodiments, each of the second plurality of fibersproduced from at least one of date tree leaves and date tree leaf stemshas a diameter in the range of 0.5 millimeters (mm) to about 1 mm. Insome embodiments, the first plurality of fibers include a firstplurality of untreated fibers and the second plurality of fibersproduced include a second plurality of untreated fibers.

In some embodiments, a method of forming a lost circulation material(LCM) is provided. The method includes grinding date tree trunks toproduce a first plurality of fibers and grinding date tree leaves, leafstems, or a combination thereof to produce a second plurality of fibers.The method further includes mixing a first amount of the first pluralityof fibers and the second amount of the second plurality of fibers toform the LCM. In some embodiments, the method includes washing the datetree trunks before grinding date tree trunks and washing the date treeleaves, leaf stems, or a combination thereof before grinding the datetree leaves, the leaf stems, or a combination thereof. In someembodiments, the method includes crushing the date tree trunks toproduce the first plurality of fibers, such that the crushing isperformed during the grinding and crushing the date tree leaves, leafstems, or a combination thereof to produce the second plurality offibers, such that the crushing is performed during the grinding. In someembodiments, the first amount of the first plurality of fibers are 30%by weight of the LCM and the second amount of the second plurality offibers are 70% by weight of the LCM. In some embodiments each of thefirst plurality of fibers has a diameter in the range of 0.4 millimeters(mm) to about 0.8 mm. In some embodiments, each of the second pluralityof fibers has a diameter in the range of 0.5 millimeters (mm) to about 1mm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph of date tree trunks of date tree leaves and leafstems from deceased date trees in accordance with an embodiment of thedisclosure;

FIG. 2 is a photograph of date tree trunks from deceased date trees inaccordance with an embodiment of the disclosure;

FIG. 3 is a schematic diagram illustrating a fiber network formed byfibers produced from date tree leaves and leaf stems;

FIG. 4 is a schematic diagram of a fiber network formed by the date treeleaf and leaf stem fibers and fibers produced from date tree trunks inaccordance with an embodiment of the disclosure; and

FIG. 5 is a process for the production and use of a date tree fiber mixLCM in accordance with an embodiment of the disclosure.

DETAILED DESCRIPTION

The present disclosure will now be described more fully with referenceto the accompanying drawings, which illustrate embodiments of thedisclosure. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to the illustratedembodiments. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art.

As a wellbore is drilled, a drilling fluid is continuously pumped intothe wellbore to clear and clean the wellbore and the filings. Thedrilling fluid is pumped from a mud pit into the wellbore and returnsagain to the surface. A lost circulation zone is encountered when theflow rate of the drilling fluid that returns to the surface is less thanthe flow rate of the drilling fluid pumped into the wellbore. It is thisreduction or absence of returning drilling fluid that is referred to aslost circulation.

Embodiments of the disclosure include a date tree fiber mix LCM thatincludes a mix of date tree fibers obtained from date tree waste tomitigate or prevent lost circulation in a well, as well as provideseepage control and minimize or prevent fluid loss. As used in thedisclosure, the term date tree waste refers to the waste produced fromfarming and processing date trees (also referred to as “date palms”),such as in the production of date fruits (also referred to as “dates”).In some embodiments, the date tree fiber mix LCM is a binary fiber mixthat includes fibers formed from date tree trunks and fibers formed fromdate tree leaves and leaf stems.

FIG. 1 is a photograph 100 of date tree leaves and leaf stems fromdeceased date trees in accordance with an embodiment of the disclosure.As discussed in the disclosure, fibers manufactured from the date treeleaves and leaf stems may be relatively tough and inflexible as comparedto the fibers manufactured from date tree trunks. FIG. 2 is a photograph200 of date tree trunks from deceased date trees in accordance with anembodiment of the disclosure. As discussed in the disclosure, fibersmanufactured from the date tree trunks may be relatively flexible, soft,bendable, and adaptable as compared to the fibers manufactured from datetree leaves and leaf stems

With the foregoing in mind, a date tree fiber mix LCM may, in someembodiments, include a binary fiber mix having fibers manufactured fromdate tree leaves and leaf stems and fibers manufactured from date treetrunks. In some embodiments, a date tree fiber mix LCM may include 30%by weight date tree trunk fibers and 70% by weight date tree leaf andleaf stem fibers. In some embodiments, the date tree fiber mix LCM mayinclude 40% by weight date tree trunk fibers and 60% by weight date treeleaf and leaf stem fibers. In some embodiments, the date tree fiber mixLCM may include 50% by weight date tree trunk fibers and 50% by weightdate tree leaf and leaf stem fibers.

In some embodiments, the date tree fiber mix LCM may include fibershaving an aspect ratio in the range of about 5 to about 50. In someembodiments, the date tree trunk fibers may include fibers having thefollowing distribution, as determined by the diameters of the fiberspassed or retained in mesh openings: about 35% to about 55% of fiberspassing through sieve mesh no. 10 and retained in sieve mesh no. 18,about 35% to about 55% of fibers passing through sieve mesh no. 18 andretained in sieve mesh no. 60, and about 5% to about 15% of fiberspassing through sieve mesh no. 60 and retained in sieve mesh no. 200. Insome embodiments, the date tree trunk fibers have diameters in the rangeof about 0.4 mm to about 0.8 mm with an average diameter of about 0.6mm. In some embodiments, date tree leaf and leaf stem fibers may includefibers having the following distribution, as determined by the diametersof the fibers passed or retained in the mesh openings: about 55% toabout 75% of fibers passing through sieve mesh no. 10 and retained insieve mesh no. 18, about 15% to about 35% of fibers passing throughsieve mesh no. 18 and retained in sieve mesh no. 60, and about 4% toabout 16% of fibers passing through sieve mesh no. 60 and retained insieve mesh no. 200. In some embodiments, the date tree leaf and leafstem fibers have diameters in the range of about 0.5 mm to about 1 mmwith an average diameter of about 0.75 mm.

The presence of two types of fibers with different physiomechanicalproperties may enable the date tree fiber mix LCM to form tightly packedplugs and seals in cracks and fractures in loss zones to provideimproved control of the loss of whole mud from the borehole to thesurrounding formation, as compared to conventional and existing fiberLCMs. For example, FIG. 3 is a schematic diagram illustrating a fibernetwork 300 formed by fibers manufactured from date tree leaves and leafstems. The fiber network 300 illustrates a relatively larger meshnetwork formed by the relatively tough and inflexible date tree leaf andleaf stem fibers, as compared to more flexible fibers. In contrast, FIG.4 is a schematic diagram of a fiber network formed by the date tree leafand leaf stem fibers and fibers produced from date tree trunks inaccordance with an embodiment of the disclosure. The fiber network 400illustrates the interlacing and interweaving enabled by the relativelyflexible date tree trunk fibers. The fiber network 400 may provide forthe formation of tightly packed, rigid, low permeability and pressuretolerant plugs and seals within the fractures, gaps, fissures, cracks,faults and other openings of a formation to prevent the loss of wholemud during drilling or other operations. In some embodiments, the fibernetwork 400 may be capable of blocking fractures, gaps, fissures,cracks, faults and other openings having a size of 3 millimeters (mm) orless at their most narrow portion, such that the fiber network 400 cancreate a flow barrier to completely prevent whole mud losses or, in someinstances, partially prevent whole mud losses, depending on the natureof subsurface loss zone. The combination of both types of fibers mayimprove the flow barrier properties of the date tree fiber mix LCM ascompared to a single fiber LCM, due to the different physiomechanicalproperties of the each type of fiber in the mix. For example, the fibernetwork 400 may be a relatively finer mesh than a fiber network formedby a single fiber LCM. The fiber network may have improved mechanicalstrength, load bearing capacity, and pressure tolerance as compared to asingle fiber LCM.

EXAMPLES

The following examples are included to demonstrate embodiments of thedisclosure. It should be appreciated by those of skill in the art thatthe techniques and compositions disclosed in the example which followsrepresents techniques and compositions discovered to function well inthe practice of the disclosure, and thus can be considered to constitutemodes for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or a similar result without departing from the spirit and scope ofthe disclosure.

The following non-limiting examples of a date tree fiber mix LCM wereprepared and evaluated against a commercially available LCM. Pluggingefficiency tests were conducted on the date tree fiber mix LCM and acommercially available LCM using a 2 millimeter (mm) slotted disc and aPermeability Plugging Tester (also referred to as “PPT” or “PorePlugging Test” apparatus) manufactured by OFI Testing Equipment, Inc.,of Houston, Tex., USA. The tests were conducted at conditions of about212° F. and about 1000 psi differential pressure. For the pluggingefficiency tests, the date tree fiber mix LCM and commercially availableLCMs were incorporated into a 65 pounds per cubic foot (pcf) bentonitemud. The composition of the 65 pcf bentonite mud with mud componentsexpressed in pounds-per-barrels (lb/bbl) is shown in Table 1:

TABLE 1 Composition of 65 pcf bentonite mud Mud Component lb/bbl Water340.67 Bentonite 25.00 Caustic Soda 0.25 Soda Ash 0.25

Three example formulations of a date tree fiber mix LCM were preparedand tested. The date tree trunk fibers used in the formulations haddiameters in the range of about 0.4 mm to about 0.8 mm with an averagediameter of about 0.6 mm. The date tree fibers used in the formulationshad the following distribution, as determined by the diameters of thefibers passed or retained in mesh openings: about 35% to about 55% offibers passing through sieve mesh no. 10 and retained in sieve mesh no.18, about 35% to about 55% of fibers passing through sieve mesh no. 18and retained in sieve mesh no. 60, and about 5% to about 15% of fiberspassing through sieve mesh no. 60 and retained in sieve mesh no. 200.The date tree leaf and leaf stem fibers used in the formulations haddiameters in the range of about 0.5 mm to about 1 mm with an averagediameter of about 0.75 mm. The date tree leaf and leaf stem fibers usedin the formulations had the following distribution, as determined by thediameters of the fibers passed or retained in the mesh openings: about55% to about 75% of fibers passing through sieve mesh no. 10 andretained in sieve mesh no. 18, about 15% to about 35% of fibers passingthrough sieve mesh no. 18 and retained in sieve mesh no. 60, and about4% to about 16% of fibers passing through sieve mesh no. 60 and retainedin sieve mesh no. 200

A first formulation was prepared from 30% by weight date tree trunkfibers and 70% by weight date tree leaf and leaf stem fibers. A secondformulation was prepared from 40% by weight date tree trunk fibers and60% by weight date tree leaf and leaf stem fibers. A third formulationwas prepared from 50% by weight date tree trunk fibers and 50% by weightdate tree leaf and leaf stem fibers. The example formulations wereevaluated to determine the improvement to the sealing and pluggingcapacity of the date tree trunk fibers provided by the variouspercentages of the date tree leaf and leaf stem fibers. The threeexample date tree fiber mix LCM formulations, a single fiber LCMformulation having 100% date tree trunk fibers, and a commerciallyavailable LCM were tested using the Permeability Plugging Testerapparatus and the following plugging efficiency test procedure:

1. Set the temperature controller/thermostat to the testing temperature;

2. Check the condition of the O-rings in the groove at the top of thetest cell of the Permeability Plugging Tester apparatus and in the cellend cap and replace the O-rings if needed;

3. Apply a thin coating of high temperature grease to all the O-rings,including the two O-rings on the piston of the Permeability PluggingTester apparatus;

4. Screw the T-bar of the Permeability Plugging Tester apparatus intothe piston, install into the bottom end of the test cell, position thepiston about 1 inch into the cell bore, and remove the T-bar;

5. Add a volume of hydraulic oil to the test cell using the hydraulichand pump of the Permeability Plugging Tester apparatus;

6. Install all the O-rings and secure the end cap of the cell inposition such that oil flows from the hole in the end cap to ensure noair is trapped;

7. Install the valve stem into the bottom end cap of the cell, tightenthe valve stem, and disconnect from the hydraulic hand pump of thePermeability Plugging Tester apparatus;

8. Place the cell upright on a suitable stand;

9. Pour a test sample of a homogenous mixture of 275 ml of the 65 pcfbentonite mud and 30 grams of an LCM into the test cell;

10. Install an O-ring into the top of the cell below the 2 mm slotteddisc;

11. Place the 2 mm slotted disc on top of the O-ring;

12. Insert the end cap on the top of the disc, screw down the threadedretaining ring, and fully tighten;

13. Tighten the top stem of the test cell;

14. Place the cell into the heating jacket of the Permeability PluggingTester apparatus;

15. Connect a pressure hose from the hydraulic hand pump to the bottomof the test cell via a quick connector and ensure the bottom stem isclosed;

16. Connect the back pressure hose/sample collector to the top stem ofthe test cell, ensuring that the locking pin is in place, close thepressure relief valve on the side of the hydraulic hand pump, apply thetesting pressure via the back pressure regulator to the top of the testcell, and close the top valve.

17. Place a thermometer into the hole at the top of the test cell. waituntil the testing temperature is reached, and monitor the cell pressurewhile heating and bleed off pressure if necessary by opening thepressure relived valve on the side of the hydraulic hand pump;

18. Once the test sample has reached the testing temperature, pump thehydraulic hand pump until the pump gauge shows the testing pressure plusthe required back pressure;

19. Apply the required back pressure to the top of the cell, open thetop valve, and pump the hydraulic hand pump to reestablish the testingpressure;

20. To determine the spurt volume, collect the fluid from the backpressure collector in a measuring cylinder and record the amount,ensuring that all the fluid has been expelled;

21. Collect the fluid periodically over a 30 minute time period andcheck the back pressure gauge to ensure that the pressure remains lessthan the pressure threshold (about 3000 psi) of the built-in safety discof the Permeability Plugging Tester apparatus and avoid expulsion of hothydraulic oil;

22. Record the spurt loss, total leak off, and PPT values over the 30minute time period and record the cake thickness after dismantling thetest cell.

The three formulations of the date tree fiber mix LCM were testedagainst a commercially available cellulosic fiber and flake LCM,STOPLOSS® manufactured by Drilchem of Jakarta, Indonesia. Table 2 showsthe results of plugging efficiency tests for the single fiber LCM at 30pounds-per-barrel (ppb) concentrations in the 65 pcf bentonite mud, thethree example, formulations of the date tree fiber mix LCM at 30 ppbconcentrations in the 65 pcf bentonite mud, and STOPLOSS® at a 30 ppbconcentration in the 65 pcf bentonite mud, with the spurt loss, fluidloss, total leak off, and PPT value measured in cubic centimeters (cc)and the cake thickness measured in mm:

TABLE 2 Plugging Efficiency Test Results for Date tree fiber mix LCM andCommercially Available LCM Total Cake PPT Spurt Loss Fluid Loss Leak OffThickness Value LCM Concentration (cc) (cc) (cc) (mm) (cc) 100% Datetree 30 ppb 2 30 32 6.32 64 trunk fibers 30% Date tree 30 ppb 1.3 9 10.322.2 20.6 trunk fibers: 70% date tree leaf and leaf stem fibers 40% Datetree 30 ppb 1 12 13 20.2 26 trunk fibers: 60% date tree leaf and leafstem fibers 50% Date tree 30 ppb 1 16 17 17.7 34 trunk fibers: 50% datetree leaf and leaf stem fibers STOPLOSS ® 30 ppb 0.7 16 16.7 3.97 33.4

As shown in Table 2, the single fiber LCM having 100% date tree trunkfibers allowed significant fluid loss and failed to prevent fluid fromescaping before sealing the slots of the disc in the PPT apparatus andstopping the loss of whole mud. The relatively flexible and bendabledate tree trunk fibers of the single fiber LCM required a longer time tocreate an effective flow barrier in the disc slots. As also shown inTable 2, due to the relatively higher compressibility of the date treetrunk fibers, the resulting cake formed during the plugging efficiencytests was less thick than the cake formed by the three date tree fibermix LCM formulations. The addition of the relatively strong andinflexible date tree leaf and leaf stem fibers in the example date treefiber mix LCM formulations enable the quicker formation of an effectiveflow barrier in the slots of the PPT disc and thus significantly reducedfluid loss, as compared to the LCM having 100% date tree trunk fibers.Thus, the blending of date tree trunk fibers and date tree leaf and leafstem fibers may improve the barrier-forming characteristics of the LCMformed from date tree fibers.

As shown in Table 2, each of the three date tree fiber mix LCMformulations exhibited reduced spurt loss and fluid loss as compared tothe LCM having 100% date tree trunk fibers. Moreover, the total leak offdecreased as the amount of date tree leaf and leaf stem fibersincreases, thus further demonstrating the technical improvement to theLCM of the addition of the date tree leaf and leaf stem fibers.

As further shown in Table 2, the 30:70 and 40:60 date tree fiber mix LCMformulations showed superior performance as compared to the STOPLOSS®commercially available LCM. The 30:70 and 40:60 date tree fiber mix LCMexhibited reduced fluid loss, reduced total leak off, and formed athicker cake than the STOPLOSS® commercially available LCM. As alsoshown in Table 2, the 50:50 date tree fiber mix LCM formulation showedcomparable performance to the STOPLOSS® commercially available LCM.Thus, all three tree waste fiber mix LCM formulations may be viablealternatives to commercially available LCMs. As shown by the negligiblespurt loss, negligible fluid loss, and negligible leak off, the 30 ppbconcentrations of the example date tree fiber mix LCM formulationsdemonstrated the ability to seal a potential loss zone quickly with anegligible loss of whole mud into the loss zone under a 1000 psidifferential pressure.

Date Tree Fiber Mix LCM Manufacture and Use

In some embodiments, a date tree fiber mix LCM may include date treetrunk fibers and a date tree leaf and leaf stem fibers. The date treetrunk fibers include fibers manufactured from date tree trunks, and thedate tree leaf and leaf stem fibers include fibers manufactured fromdate tree leaves and leaf stems. The date tree trunks and date treeleaves and leaf stems may be obtained from date tree waste produced as awaste by-product from date tree farming and date processing. The datetree waste may be obtained from pruning waste and date processing plantsto provide a sustainable source of material for the date tree fiber mixLCM. Moreover, local sources of date tree waste may reduce the cost ofimported LCM products, components, or both. In some embodiments, thedate tree trunks and date tree leaves and leaf stems may be obtainedfrom the species phoenix daciylifera. It should be appreciated that, insome embodiments, the date tree trunks and date tree leaves and leafstems may be obtained from genetically modified date trees (that is,genetically modified organisms (GMOs)). In some embodiments, the datetree trunks and date tree leaves and leaf stems may be prepared bycleaning the date tree trunks and date tree leaves and leaf stems beforeuse or processing, such as by washing the date tree trunks and date treeleaves and leaf stems.

In some embodiments, the date tree trunk fibers may include fibershaving the following distribution, as determined by the diameters of thefibers passed or retained in mesh openings: about 35% to about 55% offibers passing through sieve mesh no. 10 and retained in sieve mesh no.18, about 35% to about 55% of fibers passing through sieve mesh no. 18and retained in sieve mesh no. 60, and about 5% to about 15% of fiberspassing through sieve mesh no. 60 and retained in sieve mesh no. 200. Insome embodiments, the date tree trunk fibers have diameters in the rangeof about 0.4 mm to about 0.8 mm with an average diameter of about 0.6mm. In some embodiments, date tree leaf and leaf stem fibers may includefibers having the following distribution, as determined by the diametersof the fibers passed or retained in mesh openings: about 55% to about75% of fibers passing through sieve mesh no. 10 and retained in sievemesh no. 18, about 15% to about 35% of fibers passing through sieve meshno. 18 and retained in sieve mesh no. 60, and about 4% to about 16% offibers passing through sieve mesh no. 60 and retained in sieve mesh no.200. In some embodiments, the date tree leaf and leaf stem fibers havediameters in the range of about 0.5 mm to about 1 mm with an averagediameter of about 0.75 mm.

In some embodiments, the date tree fiber mix LCM is a binary mix of datetree trunk fibers and a date tree leaf and leaf stem fibers. In someembodiments, the date tree fiber mix LCM may include 30% by weight datetree trunk fibers and 70% by weight date tree leaf and leaf stem fibers.In some embodiments, the date tree fiber mix LCM may include 40% byweight date tree trunk fibers and 60% by weight date tree leaf and leafstem fibers. In some embodiments, the date tree fiber mix LCM mayinclude 50% by weight date tree trunk fibers and 50% by weight date treeleaf and leaf stem fibers. In other embodiments, the date tree fiber mixLCM may include 10% by weight or greater date tree trunk fibers and 90%by weight or less date tree leaf and leaf stem fibers, 20% by weight orgreater date tree trunk fibers and 80% by weight or less date tree leafand leaf stem fibers, 60% by weight or greater date tree trunk fibersand 40% by weight or less date tree leaf and leaf stem fibers, 70% byweight or greater date tree trunk fibers and 30% by weight or less datetree leaf and leaf stem fibers, 80% by weight or greater date tree trunkfibers and 30% by weight or less date tree leaf and leaf stem fibers, or90% by weight or greater date tree trunk fibers and 10% by weight orless date tree leaf and leaf stem fibers.

In some embodiments, the date tree trunks may include untreated datetree trunks, and the date tree leaf and leaf stems may include untreatedleaves and leaf stems, thus preserving the environmentally-friendly andbiodegradable properties of the manufacturing process, the date treetrunk fibers and the date tree leaf and leaf stem fibers, and theresulting LCM composition. As used in the disclosure, the term“untreated” or “without treating” refers to not treated with alkali oracid, not bleached, not chemically altered, not oxidized, and withoutany extraction or reaction process other than possibly drying of water.The term “untreated” or “without treatments” does not encompass grindingor heating to remove moisture but does encompass chemical or otherprocesses that may change the characteristics or properties of thefibers. In such embodiments, the date tree trunk fibers and date treeleaf and leaf stem fibers may be manufactured without treating before,during, or after crushing, grinding, drying, or any other processing.

In some embodiments, the date tree fiber mix LCM may be added directlyto a drilling fluid, such as a drilling mud, to create an altereddrilling fluid having the date tree fiber mix LCM. For example, in someembodiments, the date tree fiber mix LCM may be added to (for example,blended with) an oil-based drilling mud or a water-based drilling mud.In some embodiments, the date tree fiber mix LCM may be added at the mudpit of a mud system. After addition of the date tree fiber mix LCM to adrilling fluid, the altered drilling fluid may be circulated at a pumprate effective to position the altered drilling fluid into contact witha lost circulation zone in a wellbore, such that the date tree fiber mixLCM alters the lost circulation zone (for example, by entering andblocking porous and permeable paths, cracks, and fractures in aformation in the lost circulation zone, such as forming a structure in amouth or within a fracture).

As noted in the disclosure, the properties of the date tree fiber mixLCM may prevent degradation of the date tree fiber mix LCM whilecirculating downhole as a fluid loss additive or formation strengtheningmaterial. Moreover, the eco-friendly, non-toxic, and environmentallyfriendly properties of the fibers of the date tree fiber mix LCM mayminimize or prevent any environmental impact and effect on ecosystems,habitats, population, crops, and plants at or surrounding the drillingsite where the date tree fiber mix LCM is used.

FIG. 5 depicts a process 500 for the production and use of a date treefiber mix LCM in accordance with an example embodiment of thedisclosure. As shown in FIG. 5, date tree leaves and leaf stems may becollected (block 502), such as from a date tree pruning waste producedby date tree farming and date processing industries. For example, datetree pruning may be performed at regular intervals (for example,yearly), resulting in a regular collection of date tree pruning waste.In some embodiments the date tree leaves and leaf stems may be cleaned,such as by a high pressure water or air jet, to remove dirt, dust, andother foreign substances. The collected date tree leaves and leaf stemsmay be crushed and ground to produce fibers from the date tree leavesand leaf stems (block 504). In some embodiments, the collected date treeleaves and leaf stems may be crushed and ground using a suitablecommercial grinder that produces a specific range of fiber sizes (forexample, length and diameter).

As also shown in FIG. 5, deceased date tree trunks may be collected,such as from date tree waste produced at a date processing facility(block 506). In some embodiments, date tree waste may be collected froma date processing facility and transported to another facility forprocessing as described in the disclosure. In some embodiments the datetree trunks may be cleaned, such as by a high pressure water or air jet,to remove dirt, dust, and other foreign substances. The collected datetree trunks may be crushed and ground to produce fibers from the datetree trunks (block 508). In some embodiments, the collected date treetrunks may be crushed and ground using a suitable commercial grinderthat produces a specific range of fiber sizes (for example, length anddiameter).

The date tree leaf and leaf stem fibers and the date tree trunk fibersmay then be mixed to form a date tree fiber mix LCM having both fibers(block 510). In some embodiments, the mix of date tree leaf and leafstem fibers and the date tree trunk fibers may be dried and packed fortransportation and use (block 512). For example, the date tree leaf andleaf stem fibers and the date tree trunk fibers may be packed inwater-proof bags containing about 25 kilograms (kg) of the mixed fibers.In some embodiments, the date tree leaf and leaf stem fibers and thedate tree trunk fibers may be dried using a sun drying process over atime period in atmospheric conditions. In some embodiments, a suitableamount of packed mixed fibers may then be transported to an oil and gasoperations site for use as a date tree fiber mix LCM.

In some embodiments, the date tree fiber mix LCM may be added directlyto a drilling fluid (block 514), such as a drilling mud, to create analtered drilling fluid having the date tree fiber mix LCM. For example,in some embodiments, the date tree fiber mix LCM may be added to (forexample, blended with) an oil-based drilling mud or a water-baseddrilling mud. In some embodiments, the date tree fiber mix LCM may beadded at the mud pit of a mud system. After addition of the date treefiber mix LCM to a drilling fluid, the altered drilling fluid may becirculated at a pump rate effective to position the drilling fluid intocontact with a lost circulation zone in a wellbore, such that the datetree fiber mix LCM alters the lost circulation zone (for example, byentering and blocking porous and permeable paths, cracks, and fracturesin a formation in the lost circulation zone). As previously stated, thedate tree fiber mix LCM may form a fiber network at openings of paths,cracks, and fractures in a loss zone. In some embodiments, the reducedrate of lost circulation may be negligible. In some embodiments, thedate tree fiber mix LCM may be introduced via an open ended drill pipeto place the LCM in the lost circulation zone

In other embodiments, the date tree fiber mix LCM and one or moreadditional LCMs may be added to a drilling fluid, such as a drillingmud, to create an altered drilling fluid having the LCMs. For example,in some embodiments, the date tree fiber mix LCM and one or moreadditional LCMs may be added to an oil-based drilling mud or awater-based drilling mud. In other embodiments, the date tree fiber mixLCM may be added to a cement slurry for use in a cementing operation.

The biodegradation properties of the date tree leaf and leaf stem fibersand the date tree trunk fibers of the date tree fiber mix LCM may enablethe date tree fiber mix LCM to easily degrade and disappear from theenvironment over time and minimize or prevent any environmental impact.Further, the non-toxic properties of the date tree fibers may minimizeor prevent any effect on ecosystems, habitats, population, crops, andplants surrounding the drilling site where the date tree fiber mix LCMis used.

In some embodiments, the date tree fiber mix LCM may be mixed with acarrier fluid, a viscosifier, or both. In some embodiments, a date treefiber mix LCM homogenous suspension or pill may be formed. For example,a specific carrier fluid, viscosifier, or combination thereof may beselected to form a homogenous suspension or pill having the date treefiber mix LCM. The homogenous suspension or pill may be added to adrilling fluid and used in the manner similar to the date tree fiber mixLCM described in the disclosure.

Ranges may be expressed in the disclosure as from about one particularvalue, to about another particular value, or both. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value, to the other particular value, or both, along withall combinations within said range.

Further modifications and alternative embodiments of various aspects ofthe disclosure will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the embodiments described inthe disclosure. It is to be understood that the forms shown anddescribed in the disclosure are to be taken as examples of embodiments.Elements and materials may be substituted for those illustrated anddescribed in the disclosure, parts and processes may be reversed oromitted, and certain features may be utilized independently, all aswould be apparent to one skilled in the art after having the benefit ofthis description. Changes may be made in the elements described in thedisclosure without departing from the spirit and scope of the disclosureas described in the following claims. Headings used described in thedisclosure are for organizational purposes only and are not meant to beused to limit the scope of the description.

What is claimed is:
 1. A method to control lost circulation in a lostcirculation zone in a wellbore, comprising: introducing an altereddrilling fluid into the wellbore such that the altered drilling fluidcontacts the lost circulation zone and reduces a rate of lostcirculation into the lost circulation zone, where the altered drillingfluid comprises a drilling fluid and a lost circulation material (LCM),wherein the LCM comprises: a first plurality of fibers produced fromdate tree trunks; and a second plurality of fibers produced from atleast one of date tree leaves and date tree leaf stems.
 2. The method ofclaim 1, wherein the altered drilling fluid consists of the drillingfluid and the LCM.
 3. The method of claim 1, wherein the LCM consists ofthe first plurality of fibers produced from date tree trunks and thesecond plurality of fibers produced from at least one of date treeleaves and date tree leaf stems.
 4. The method of claim 1, wherein thefirst plurality of fibers comprise 30% by weight of the LCM and thesecond plurality of fibers comprise 70% by weight of the LCM.
 5. Themethod of claim 1, wherein the LCM comprises a concentration of at least30 pounds-per-barrel (ppb) in the altered drilling fluid.
 6. The methodof claim 1, wherein each of the first plurality of fibers produced fromdate tree trunks has a diameter in the range of 0.4 millimeters (mm) toabout 0.8 mm.
 7. The method of claim 1, wherein each of the secondplurality of fibers produced from at least one of date tree leaves anddate tree leaf stems has a diameter in the range of 0.5 millimeters (mm)to about 1 mm.
 8. The method of claim 1, wherein the first plurality offibers comprise a first plurality of untreated fibers and the secondplurality of fibers produced comprise a second plurality of untreatedfibers.
 9. An altered drilling fluid, comprising: a drilling fluid; anda lost circulation material (LCM), wherein the LCM comprises: a firstplurality of fibers produced from date tree trunks; and a secondplurality of fibers produced from at least one of date tree leaves anddate tree leaf stems.
 10. The altered drilling fluid of claim 9, whereinthe LCM consists of the first plurality of fibers produced from datetree trunks and the second plurality of fibers produced from at leastone of date tree leaves and date tree leaf stems.
 11. The altereddrilling fluid of claim 9, wherein the first plurality of fiberscomprise 30% by weight of the LCM and the second plurality of fiberscomprise 70% by weight of the LCM.
 12. The altered drilling fluid ofclaim 9, wherein the LCM comprises a concentration of at least 30pounds-per-barrel (ppb) in the altered drilling fluid.
 13. The altereddrilling fluid of claim 9, wherein each of the first plurality of fibersproduced from date tree trunks has a diameter in the range of 0.4millimeters (mm) to about 0.8 mm.
 14. The altered drilling fluid ofclaim 9, wherein each of the second plurality of fibers produced from atleast one of date tree leaves and date tree leaf stems has a diameter inthe range of 0.5 millimeters (mm) to about 1 mm.
 15. The altereddrilling fluid of claim 9, wherein the first plurality of fiberscomprise a first plurality of untreated fibers and the second pluralityof fibers produced comprise a second plurality of untreated fibers. 16.A lost circulation material (LCM) composition, the compositioncomprising: a first plurality of fibers produced from date tree trunks;and a second plurality of fibers produced from at least one of date treeleaves and date tree leaf stems.
 17. The LCM of claim 16, consisting ofthe first plurality of fibers produced from date tree trunks and thesecond plurality of fibers produced from at least one of date treeleaves and date tree leaf stems.
 18. The LCM of claim 16, wherein thefirst plurality of fibers comprise 50% by weight of the LCM and thesecond plurality of fibers comprise 50% by weight of the LCM.
 19. TheLCM of claim 16, wherein each of the first plurality of fibers producedfrom date tree trunks has a diameter in the range of 0.4 millimeters(mm) to about 0.8 mm.
 20. The LCM of claim 16, wherein each of thesecond plurality of fibers produced from at least one of date treeleaves and date tree leaf stems has a diameter in the range of 0.5millimeters (mm) to about 1 mm.
 21. The LCM of claim 16, wherein thefirst plurality of fibers comprise a first plurality of untreated fibersand the second plurality of fibers produced comprise a second pluralityof untreated fibers.
 22. A method of forming a lost circulation material(LCM), comprising: grinding date tree trunks to produce a firstplurality of fibers; grinding date tree leaves, leaf stems, or acombination thereof to produce a second plurality of fibers; mixing afirst amount of the first plurality of fibers and a second amount of thesecond plurality of fibers to form the LCM.
 23. The method of claim 22,comprising: washing the date tree trunks before grinding the date treetrunks; and washing the date tree leaves, leaf stems, or a combinationthereof before grinding the date tree leaves, the leaf stems, or acombination thereof.
 24. The method of claim 22, comprising: crushingthe date tree trunks to produce the first plurality of fibers, whereinthe crushing is performed during the grinding; and crushing the datetree leaves, leaf stems, or a combination thereof to produce the secondplurality of fibers, wherein the crushing is performed during thegrinding.
 25. The method of claim 22, wherein the first amount of thefirst plurality of fibers comprises 30% by weight of the LCM and thesecond amount of the second plurality of fibers comprises 70% by weightof the LCM.
 26. The method of claim 22, wherein each of the firstplurality of fibers has a diameter in the range of 0.4 millimeters (mm)to about 0.8 mm.
 27. The method of claim 22, wherein each of the secondplurality of fibers has a diameter in the range of 0.5 millimeters (mm)to about 1 mm.